But, hey, maybe that’s because her Jamie is a tough New York headhunter and his Dylan is the dreamy Angelino web guru who heads east for a job she found him as art director of GQ magazine. Despite growing up on opposite ends of the country, the chemistry between the two is undeniable to everyone but them, which is the reason for keeping it going for almost 100 minutes of amusing adult entertainment.

After becoming buddies and deciding to have a fling with “no strings attached” (and this is a much better film than that similarly themed early-year romp), their sex becomes frequent and never boring. Predictably, the “L” word crops up as nature takes its course, but not without a slew of references to other rom-coms, counting a few good ones (“Pretty Woman,” “Bob & Ted & Carol & Alice”), one bad (placing Jason Segel opposite Rashida Jones, and apparently made just so Jamie and Dylan can watch and make fun of it), and even “The Ugly Truth.”

Obviously, director and co-writer Will Gluck understands what can and won’t make the genre tick. Coming off last year’s surprisingly droll teen comedy (“Easy A”), he even coaxed his now-risen star, Emma Stone, to help open “Benefits” as part of a double-barreled cameo bit. She plays the John Mayer-obsessed girlfriend who dispatches Dylan on Hollywood Boulevard, about the same time Jamie gets dumped by her squeeze (“SNL” regular Andy Samberg), in front of a Big Apple movie house.

The two big cities, by the way, share some nice-looking moments with their photogenic lead stars, who somehow find time to chat/spar/love in various landmark locations on both coasts.

Justin's Dylan and Mila's Jamie develop a unique "Friends"-ship.

Supporting cast members rate a big mention, too, especially Patricia Clarkson, as Jamie’s free-spirited mom (from Cleveland, no less), and Richard Jenkins, as Dylan’s ailing dad. Jenna Elfman fares well as a big sister, but Woody Harrelson, alas, seems woefully miscast in his ultra-goofy role as a gay and very randy sports editor.

Many of the movie’s other running gags — Dylan’s problems with calling famous airline Capt. Sully Sullenberger a hero; a couple of hilarious run-ins with X-Games Olympian Shaun White; some fine references to an under-rated Semisonic song called “Closing Time” — play much more beneficially. In other words, these “Friends” certainly know how to have and inspire fun.